The present invention relates generally to scroll compressors and more specifically to such scroll compressors incorporating discharge valving for preventing reverse orbital motion thereof.
Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft. Because scroll compressors depend upon a seal created between opposed flank surfaces of the wraps to define successive chambers for compression, suction and discharge valves are generally not required. However, when such compressors are shut down, either intentionally as a result of the demand being satisfied or unintentionally as a result of a power interruption, there is a strong tendency for backflow of compressed gas from the system in combination with high pressure gas contained in the chambers and/or discharge muffler to effect a reverse orbital movement of the orbiting scroll member and associated drive shaft. This reverse movement often generates objectionable noise or rumble. Further, in machines employing a single phase drive motor, it is possible for the compressor to begin running in the reverse direction should a momentary power failure be experienced.
In order to limit such reverse rotation, scroll compressors have incorporated ball type check valves at the point of connection between the outer shell and discharge line. While such ball type check valves have been effective to limit backflow of compressed refrigerant, they have demonstrated a tendency to vibrate or chatter under certain flow conditions thus presenting a further source of objectionable noise. Also, in severe situations, the chattering may result in damage or destruction of the ball stop and/or seat. Additionally, the occasional discharge of liquid through such ball type check valves further increases the possibility of damage thereto.
The present invention overcomes these problems by incorporating a disc type check valve in the outlet from the outer shell which effectively prevents return flow of compressed gas from the refrigeration system and hence limits reverse orbital movement of the orbiting scroll member. Because reverse orbital movement is thus limited, the possibility of objectionable noise being generated thereby upon shut down of the compressor is greatly reduced. The disc type discharge valve does not require any biasing means but rather operates to create a pressure differential thereacross which moves the disc between seated and unseated positions. The disc type discharge valve of the present invention provides an inexpensive, easily installed means to effectively resist reverse movement of the orbiting scroll. Further, because a relatively large stop surface area is provided extending around the periphery of the valve member, the possibility of damage from discharge of liquid therethrough is greatly reduced. In one form, the disc type discharge valve is specifically designed to be secured to the outer shell by spin welding.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.